1. Field of the Invention
The present invention relates to a flat panel display system and an image signal interface method thereof, and more particularly, to a flat panel display system in which the interface for transmitting the image signal to a flat panel display device like a liquid crystal display module is accomplished by a low voltage differential signal (LVDS) specification, to thereby reduce the number of components and transmission lines and an electromagnetic interference (EMI), and an image signal interface method of such a flat panel display system.
2. Description of the Related Art
Recently, flat panel display devices are being developed to have a high frequency and a high resolution for achieving a better screen.
Liquid crystal display (LCD) modules are the representative flat panel display device. However, XGA or higher level LCD modules have difficulties in achieving a high resolution due to an EMI problem and a noise generated by the transmission medium, and the restriction in the number of data transmission bits.
In a conventional flat panel display device, data transmission is performed at a transistor-transistor logic (TTL) level, and an image signal has a high frequency under such an environment. In addition, a voltage level is shifted to the corresponding frequency, which causes EMI problem.
The data or clock signal transmission method performed at TTL level requires a large number of transmission paths. As the number of cables or connectors increase, such cables or connectors tend to be increasingly exposed to an external noise source. Therefore, if such cables or connectors are exposed to the external noise source, the noise may affect the normal data and clock signal. As a result, the screen becomes abnormal.
The number of data transmission bits supported by a graphic controller for achieving a full color high resolution is restricted. Thus, it is not easy to obtain a high resolution with 260,000 colors or more using a method where two channels are used.
To solve such a problem, the LVDS specification for an interface between the main body of the computer and the LCD module has been proposed. The LVDS specification is a new data interface standard that is defined in the IEEE 1596.3 standards. It is essentially a signaling method used for a low-voltage and high-speed data transmission.
LVDS technology provides a narrow band high-speed interface between the LCD module mounted in a notebook computer and a graphic controller of a motherboard, or uses a long cable for a monitor of a desktop computer.
LVDS technology is applied to the conventional image signal interface of flat panel display system having the structure shown in FIGS. 1 or 2.
Referring to FIG. 1, a low-voltage differential signal transmitting unit 10 converts an image data and a control signal into a low-voltage differential signal, and transmits the same to a low-voltage differential signal receiving unit 12. Here, the low-voltage differential signal transmitting unit 10 belongs to the main body of the notebook computer while the low-voltage differential signal receiving unit 12, a timing controller 14, and a driver IC 16 belong to the LCD module.
The low-voltage differential signal transmitted from the low-voltage differential signal transmitting unit 10 is converted to a TTL signal at the low-voltage differential signal receiving unit 12, and the TTL signal output from the low-voltage differential signal receiving unit 12 is controlled by the timing controller 14 so as to be converted in its timing format and is applied to a driver IC 16.
Referring to FIG. 2, a low-voltage differential signal transmitting unit 20 converts the image data and the control signal to a low-voltage differential signal and transmits the same to a one-chip IC 22. Here, as described above, the low-voltage differential signal transmitting unit 20 belongs to the main body of the notebook computer while the one-chip IC 22 and the driver IC 24 belong to the LCD module.
The one-chip IC 22 is constructed to perform both the function of a low-voltage differential signal receiver and a timing controller. Thus, the one-chip IC 22 converts the input low-voltage differential signal to a TTL level, and further converts them into the timing format. Then, the TTL signal the timing format of which is converted is applied to the driver IC 24.
The conventional image signal interface of a flat panel display system as shown in FIGS. 1 and 2, requires a plurality of component blocks and peripheral passive elements for the LCD module. Specifically, the timing controller 12 and the one-chip IC 22 required for timing format are interfaced with the driver ICs 16 and 24 through the high frequency TTL signal, which are likely to generate EMI and a noise.
Moreover, when interfacing the image signal with the conventional LCD module, the data is transmitted to the driver IC by the TTL signal, which requires a considerable number of data transmission lines. Accordingly, the design becomes complicated and the printed circuit board (PCB) having four or more layers is required, which increases the production cost.
Further, a large number of data transmission lines cause EMI problem, thus requiring additional components for preventing such an EMI problem.
It is therefore an object of the present invention to overcome an EMI problem caused by a transmission medium mounted on an LCD module to transmit an image signal.
It is another object of the present invention to protect the transmission medium used for an image data interface from a noise source.
It is still another object of the present invention to achieve a full color high resolution by transmitting a large amount of data via small number of transmission lines, applying the LVDS technology to an image signal interface of an LCD module.
It is yet still another object of the present invention to enhance a wiring structure by reducing the number of components and cable required for transmitting an image signal to an LCD module.
An image signal interface method of a flat panel display system according to the present invention transmits as a low-voltage differential signal an image signal including an image data from a predetermined image signal transmitting source to a composite driver IC that outputs a display signal to form a picture.
According to an aspect of the present invention, there is provided a flat panel display system including an image signal transmitting source having a low-voltage differential signal transmitting unit for converting an image signal, i.e., a TTL signal, containing an image data and a control signal, into a low-voltage differential signal, and transmitting the converted low-voltage differential signal; a one-chip IC for converting the low-voltage differential signal transmitted from the low-voltage differential signal transmitting unit to a TTL signal, converting the signal corresponding the image data to the low-voltage differential signal and transmitting the same, and converting the timing format of the signal corresponding to the control signal and transmitting the converted signal as a TTL signal; and an LCD panel having a composite driver IC to which the low-voltage differential and TTL signals of the one-chip IC are input and which outputs a signal for driving the LCD panel as a TTL signal containing the input and converted image data and control signal.
A flat panel display system according to another aspect of the present invention includes: an image signal transmitting source having a low-voltage differential signal transmitting unit for converting a first TTL signal into a low-voltage differential signal and transmitting a first low-voltage differential signal converted from a second TTL signal that includes an image data contained in the first TTL signal and a second low-voltage differential signal converted from a third TTL signal that includes a control signal contained in the first TTL signal; a one-chip IC to which the second low-voltage differential signal is input and converted to a fourth TTL signal and which converts the timing format of the fourth TTL signal and transmits a fifth TTL signal; and an LCD panel having a composite driver IC to which the first low-voltage differential signal is input so as to be converted into a sixth TTL signal, and the fifth TTL signal is input from the one-chip IC, and which outputs, as a signal for driving the LCD panel, the fifth and sixth TTL signals containing the image data and the control signal.